Reed switches are used in a variety of devices, such as, for example, relays, sensors, or the like. A reed switch includes two electrically conducting reeds where at least one of the reeds has a flexible portion. The reeds are disposed in an insulating housing with a gap between end portions of the reeds. The gap can be selectively closed to close the switch and allow conduction of electric current through the reeds. For example, magnetic force may be applied to the reeds to cause the reed with the flexible portion to deform and close the gap.
In general, the reeds are formed from sections of round wire, with the flexible portion formed by flattening a portion of one of the reeds. For example, one of the reeds may have a section flattened in a punch press to form a flexible portion. As will be appreciated, however, when the flexible portion is flattened, the cross-sectional area of the flexible portion increases. For example, FIGS. 1A-1B illustrate side and top views, respectively, of a conventional reed 100 for a reed switch. As depicted, the reed 100 includes a terminal portion 110, a flexible portion 120, and a contact pad portion 130. The flexible portion 120 and the contact pad portion 130 have been flattened. More particularly, as can be seen from FIG. 1A, the flexible portion 120 and the contact pad portion 130 are thinner than the terminal portion. However, due to the flattening processes, the flexible portion 120 and the contact pad portion 130 expand outward in a direction generally orthogonal to the direction in which the portions are flattened. More particularly, as can be seen from FIG. 1B, the flexible portion 120 and the contact pad portion 130 are wider than the terminal portion 110.
FIG. 1C illustrates a perspective view of the reed 100. As depicted, the reed is formed from a section of round wire. Terminal portion 110, flexible portion 120, and contact pad portion 130 are depicted. The flexible portion 120 and the contact pad portion 130 are thinner than the terminal portion 110, but also wider than the terminal portion 110.
To make a reed switch, the reed 100 and another reed are fixed in an insulating housing, such as, a glass tube. Typically, the reed 100 is fixed in the housing near the edge of the terminal portion 110 and the flexible portion 120. During operation, the reed 100 deforms at the flexible portion 120 and the contact pad 130 touches the other reed to close the switch and allow conduction of electric current through the reeds. However, due to the increased width of the flexible portion 120, interference with the insulating housing may prevent the reed 100 from deforming as intended.
Thus, there is a need for reeds that may not interference with the insulating housing when assembled or deformed.